Draft device for furnaces



Feb. 6, 19231 C. COLEATTI DRAFT DEVICE FOR FURNAGES Filed Oct. 28, 1919 2 sheets-sheet 2 -.\d4u. x n

u. f r/. WCL Q fhvvhnurnan,wfrfnhd-zwafmwtnnrwr NMX L Nl A MANN Patented Feb.. 6, 1923.

Unirse PATENT CARLO COLEATTI, or MILAN, ITALY.

inea Fic.

DRAFT DEVICE ron rURNAcEs.

Application filed. Getober 28, 1919. Serial No. 333,970.

` Devices for Furnaces, of which the following is a specification.

This invention relates to improved means for furnishing air and steam to furnaces.

The primary obj ect of the invention is to provide an improved apparatus for mixing air and steam andfor rapidly feeding the mixture into the furnace.

A further object of the invention is to provide an apparatus of the above character which may be applied to existing furnaces without material alteration of the latter.

l/Vith the foregoing objects outlined and with other objects in view which Vwill appear as the description proceeds, the invention consists in the novel features hereinafter described in detail, illustrated in the accompanying drawings and more particularly pointed out 'in the appended claims.

Referring to the drawings: j

Figure 1 is a front View partly in section of one form of the improved apparatus.`

Fig. 2 is a side View of the same, partly in section.

Fig. 3 is a vertical sectional View of a portion of a furnace with the form of apparatus shown in Figures 1 and 2 applied thereto.

Figure 4 is a front view partly in section of the furnace shown in Figure 3, said section being taken `on line 4-4 of Fig. 3.

In the drawings, and referring particulai-ly to Fig. 3, 1 designates a grate preferably of the kind disclosed in my prior application for patent Serial No. 333,969, filed Oct. 28, 1919. This grate is 'mounted on supports 6 arranged within the boiler, and a mixture of air and steam is 4forced into the ash pit or chamber 27 under the grate by means of the apparatus shown in Figures 1 and 2. This apparatus includes steam nozzles 7, each of which is carried by a supporting bracket 12.

The nozzles are connected, as shown in Figure 4, to a steam supply pipe 29 which extends fro-m the dome 30 of the boiler and is provided with a gage 31 anda valve 32. The brackets 12 are seculred tothe lower ends of the Venturi tubes 11, which have their upper ends connected to a blast box 13. It will be noted from Figures 1 and 2 that the nozzles 7 are arranged coaxially with the j axes of the tubes 11, and as the lower ends of the tubes 11 are open, the steam passing into said tubes entrains air and forces said air into the furnace. vOwing to the shape of the tubes, the currents of air and steam are in effect compressed during` their passage through the smallest sections of the tubes 11. Consequently the currents acquire a greater velocity, which is advantageous for the subsequent expan'sion of said currents both in the upper portions ofthe tubes 11 and in the furnace. f Further as the steam injectors are directly fixed upon the blast ducts or tubes 11, these ducts and injectors maybe readily applied to existing furnaces.'

The box 13 is of prismatic trapezoidal form as best shown in Figure 2 and the pipes 11 are connected to the largest parallel face of said box. This face is apertured as shown at 16. The wall 14 of the box is fastened over an opening formed in the front wall of the furnace at a position in alignment with the ash-pit. The wall 14 is apertured to permit the mixture of air and steam to pass from the box 13 into the ash-pit of the furnace. The opposite wall 18 is inclined downwardly and outwardly and this wall functions as av deflective plate for deflecting the air and steam currents through the opening. in the wall 14. By this construction, the formation of air pockets in the upper portion of the box-13 and the production of whirl-pools, is prevented, and the efficiency of the airandy steam currents is increased. The wall 18 is provided with a door 19 which seats on a washer or packing 15 arranged on an outwardly extending iiange 20 that surrounds an opening provided in the wall 18. A door 21 arranged in the box 13 is provided for the purpose of closing the upper ends of the tubes 11 when the furnace is to be operated with a natural draft. When `the door 21 is closed the door 19 may be opened. The door 21 is usually maintained in a position substantially parallel to the ydoor 19. To accomplish this, the door 21 rests against a projection 22. The lower end of the doo-r is provided with stub axles 23, which engage bearing projections 24 arranged within the box 13. In order to enough. away from the lug the cover may turn freely on its axle, and thus seat on the wall having the apertures 16. In connection with the furnace shown in Figs. and 4, the lbox 13 is mounted on the front wall under the grate level and preferably at the height of the ash pit 27, while the tubes 1l project downwardly. The injectors are thus arranged in a chamber 28 under the floor. Y

The operation is as follows: Steam being supplied through the pipe 29, it flows through the nozzles l and while passing into the Venturi tubes 1l, it entraine air and forces said air through the grate of the furnace. rllhe mixture of air and steam passes through the openings in the grate and emerges abovev the latter with considerable velocity owing to the special form of the air and steam feeding apparatus and to the tapered form of the grate openings.V The grate is specially formed to cause the two series of air jets to cross one another above the grate and burn the remnants of fuel which float above the fire.

lVhat l claim and desire to secure by Letters-Patent is:

l. A forced draft furnace having a grate and an ash pit arranged beneath thefsame, a box arranged on one of the walls of the furnace and communicating with the ash pit, an air conveying tube having one of its ends connected to said box and communicating therewith, a steam injector mounted at the other end of the tube and having its axis coaxial with the axisof the tube, a hinged cover arranged within the box and adapted to move parallel with the axis of its hinge, a projection positioned within the box for holding said cover in open position, said cover being adapted to close communication between thev box and the end of the tube which is connected to the same when the cover is moved parallel with the axis of its hinge to avoid said projection and' then swung downwardly, and a door for the box designed to permit the entrance of air into the box independently of the air conveying tube.

2. The combination with a furnace having an ash pit provided with an opening, of a chamber arranged on said furnace and having its interior communicating with the ash pit through said opening, the front wall of said chamberbeing inclined downwardly and outwardly away from the furnace and being provided'with an aperture to permit the rein-oval of ashes from the ash pit and to admit atmospheric air directly to said ash pit, a movable door for closing said aperture, ports arranged in the bottom of: said chamber, vertically arranged air tubes located beneath said chamber and having their interiors communicating with the interior of said vchamber through said ports, the lower ends of said tubes being open, steam. injectors arranged at the lower ends of the tubesl and each having its axis coaxial with the axis of the tube with which it cooperates, a hinged cover arranged in said chamber and, adapted to swing` and to move parallel with the axis of its hinge, a. project-ion positioned within the chamber and adapted to be engaged by the'cover for holding the `latter in open'position, said cover being adapted to close said ports when the cover is moved parallel with the axis of its hinge to avoid said projections and then swung downwardly.

3. A combination as claimed in claim 2 in which the aperture in the inclined wall of the chamber is surrounded by an outwardly extending flange, and in which said door is provided with an annular groove containing a packing strip adapted to engage said flange and insure an air tight closure for said aperture.

ln testimony whereof ll affixed signature in the presence of two witnesses.

exa-Lo ooiiaiirri.

Witnesses GIARI GIACOMO GUARNIER BoLorANIL. 

